It was all going so well until the dwarf got arrested. "That was a bit Spinal Tap," says Nikki Sixx, shaking his head. "I mean, how can you have a Rock'n'roll Circus without a midget?" Especially one who juggles, blows fire, rides a unicycle and a motorbike, emcees, wears bondage leather and gets his bottom spanked by scantily dressed dancing girls. Homeland Security took objection to his Canadian passport when the Red White and Crüe tour slipped over the US border, and held him in jail for a week. But he's back now. "And everything else," insists Sixx, "is going great."

This, to put it mildly, is a miracle. Of all the 1980s band reunions least likely to be a success, Mötley Crüe's had to be up near the top. For so many reasons. One member recently had his hip replaced (guitarist Mick Mars). One member recently had his face replaced (frontman Vince Neil). And at least three of the four members have recently declared their hatred for another member of the band (more often than not, Neil). Each travels separately in his own tour bus and has individual dressing rooms backstage. Interviews are done separately, too.

Then there's the matter of their image and music - big hair glam metal and the excessive lifestyle that accompanied it was enormous in the 1980s but a laughing stock in the 1990s after alternative rock, then nu metal, kicked it aside. For a while, Mötley Crüe were reduced to playing clubs, braving it out to the press, saying it was just to get "close to the people". The press, meanwhile, were interested only in Tommy Lee's and Sixx's Baywatch wives: Pamela Anderson (no longer married to drummer Lee) and Donna D'Errico (still married, eight years on, to bassist Sixx). Solo projects failed to match their early glory; Lee was in jail on a domestic violence charge; Neil was bloated from drink; Mars, crippled by ankylosing spondylitis, was addicted to opiates.

And then along came The Dirt. The band-sanctioned biography swiftly earned the reputation of the most notorious rock book ever. Led Zeppelin's once-untouchable Hammer of the Gods read like Heidi compared with Mötley's tales of experiments with groupies, telephones and egg burritos (you don't want to know). It was a huge bestseller. Film rights have just been sold. Remarkably, judging by the young women hanging around in the hope of backstage passes, the book seems to have attracted rather than put them off.

"We lost perspective," says Sixx. "We almost didn't survive. But isn't that what's exciting about us? That we almost didn't survive?" He puffs on a cigarette - these days, his only vice. In the 1980s, famously, he died for two minutes after a heroin overdose; the band's hit record Kickstart My Heart referred to the Pulp Fiction-style shot in the heart that revived him. He still goes to 12-step addiction meetings on the road.

"People came to the car race hoping they would see a car accident, but it doesn't mean that the race itself - meaning our music - wasn't exciting. But this is us. It's our dirt - our dirty laundry. But what's really taken us by surprise is you can hardly read a review of the band now that isn't just amazing. There are a few digs but it's mostly, 'This is just what we need.' We're really doing the same thing we were doing in the beginning, and back then it was, 'Oh my God.' It's gone from that to, 'Thank God.'"

In another dressing room off the long, concrete corridors backstage at a sports arena in San Antonio, Texas (a big heavy metal town, a big military town, too), Vince Neil suggests why the band is being so well-received: "I think music right now is very dull and too formulated. It's all boy bands and girl bands, there's really no rock bands. And there's no showmanship. It's not really entertainment. I think that's why they're into us."

Neil's new wife (his fourth), Lia Gerardini, is sitting next to him. She's just flown out to join him on the road. "Nikki has had his wife and kids come out, too," says Neil, "and Tommy's had his kids. All having our own buses, it makes it easy. I had a bar built in mine. Me and Tommy both love wine and we share a couple of glasses before and after the shows."

A strange picture, considering that the relationship between Lee and Neil almost led to bloodshed on the last reunion tour. And that US men's magazine Blender just quoted Neil as saying: "I don't like Tommy and Tommy doesn't like me ... You still do your job, huh? The secret is to think of the Eagles. They toured forever and they fucking hated each other."

"I don't remember doing that interview," Neil says with a shrug. "You know, we hadn't gotten along in a long time, but we get along great now, better than ever. Me and Tommy, we've been friends for 30 years. That's a long time - and in 30 years, you're going to have fights, but it's just like brothers, you know? Brothers fight and then you make up." Gerardini squeezes his hand. They married three months ago in a Las Vegas ceremony at which MC Hammer officiated.

Hammer is Neil's castmate on the US TV series Surreal Life. Neil has become better known, though, for another TV series, Remaking: Vince Neil. It followed the overweight singer as he went to behavioural therapists, a personal trainer, wardrobe and hair stylists, and had liposuction and a facelift. "It was great," says Neil, grinning. His face looks normal, still on the chubby side. "I remember getting this call when we were in South Beach, Florida, having cocktails, and it was my manager saying VH1 has this new show and they want to remake you. I said that sounds like a great idea, because I wasn't really doing anything - my [solo] band's tour was just ending - and you have a beer gut from drinking all the time. And this show - you couldn't fail. If after three months you look the same, you're going to look like an idiot."

Asked if guitar-player Mars (53, but looking much older) considered a makeover, Neil laughs heartily. "No. Mick's like the old trusty car that will always keep running. It might be a little rusty on the outside but the engine still works good. Anyway, he just had an extreme makeover. He had his hip replaced. He's doing pretty good."

Mars is sitting alone on his dressing room couch. At the start of the tour he was hit with a $10m palimony suit by his last girlfriend. He is thin and painfully frail, dressed all in black, from stacked shoes to sunglasses and hat. There were reports in the music press that Dave Navarro, sometime guitar-player with the Red Hot Chili Peppers and Jane's Addiction, was waiting in the wings to step in if Mars couldn't cut the tour. "There's no way if this is, like, a reunion tour you can have someone else on guitar," he says, softly. "I don't know who started that rumour. It didn't hurt me, it just pisses me off. I mean, I have this shit to deal with - I call myself Quasimodo, I make light of it - but I don't know where it's going to take me."

On his tour bus, there is an adjustable, electric hospital bed and an assistant "to watch that nothing too bad happens. Because I could break very easily. But I wouldn't turn to alcohol or opiates or anything again. It's not worth it. Those stupid little tabs - I had to use them, that's the only way to treat this, and it turned into an addiction - they wrecked my life for three or four years."

Was there any trepidation about committing himself to a two-year world tour when the stress, or the issues between Neil and Lee, might drive him back to drugs? "I never thought about it that way when they asked me. At the time, I was pretty fucked up on opiates and hip replacements and all that kind of crap to think about anything else. Of course Tommy and Vince had issues, but I think it was all aired out and taken care of, just talking among ourselves, talking with managers. And people wanted to see us back together, so it was time to do it." How much money will they earn from this tour? "I have no idea."

However much it is, Lee deserves it. Every night he's hoist into the air on a single cable tied to his trousers and swung between two high-altitude drum platforms. "I pray to God every day that the cable never breaks. I almost fell the other day." Their insurance costs the earth; one reason why Lee is not allowed to drive his own tour bus. "I asked but they won't let me." His is the "party bus". Lee is single these days. "Super single. I'm the only single guy on tour - well Mick is, but you know, with his health - so I get to play with all of the girls. I keep calling my friends. I'm like, guys, you've got to come out here and help me, there's way too much fun going on out here, I can't do it all by myself."

Like Sixx, Lee also travels with recording equipment. There are plans to record an all-new Mötley Crüe album when the tour is over - which at this rate looks like 2007. The UK leg begins in June - as opposed to the three bonus tracks recorded for their latest two-CD retrospective, Red White and Crüe.

Although Sixx folded his band, Brides of Destruction, Lee, like Neil, is keeping his solo career going. An insurance policy against the inevitable Mötley implosion? "The only thing people ask us about is if we're getting along. Of course we get along. Time heals - it's been six years. People change, grow up. I think we all have the attitude now that if we could just fucking get along instead of fucking with each other, we could continue to do this for as long as anybody wants to. It's all about communication. I learned that [in therapy when] going to jail for spousal abuse. I wish that had never happened to me, but I learned something, so it turned out to be OK. And right now this is where I want to be, and I'm having a fucking blast."

Towards the end of tonight's show, after the evil clowns, blood-spattered roadies, the prodigal dwarf on his mini motorbike, Mars getting set on fire while guitar soloing, Lee flying through the air, strobes, explosions, dry ice, aerial pole-dancing, an animated Mötley film, the Bic-waving, singalong ballad, and the "tit-cam" (that old 1980s arena rock staple, where women are encouraged to bare their breasts on screen), Sixx declares, before closing with new song If I Die Tomorrow: "This is not a fucking farewell tour." Or as Neil puts it succinctly: "We're Mötley Crüe, motherfuckers. We're back."